Agriculture Reference
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Fig. 5.4 Online and on-the-go sensing of soil electrical conductivity by electromagnetic induction.
The sensing instrument (EM 38 of Geonics LTD, Canada) can be moved on a sled, on a cart or even
be carried by hand. In order to prevent interference from metal, some distance to the vehicle is
needed (Photo from Agri Con GmbH, Jahna, Germany, altered)
primary
magn. field
container with instruments
loops of eddy-current,
created in the soil by
the primary magn. field
induced second.
magnetic field in soil
Fig. 5.5 Operating principle of soil sensing by electromagnetic induction (From Lesch et al. 2005 ,
altered and supplemented)
The sensing implement (Figs. 5.4 and 5.5 ) has two wire coils, a primary- or
transmitter coil plus a secondary- or receiver coil. The current that flows through the
transmitter coil produces a magnetic field around it. This magnetic field also extends
into the soil and thus produces there a primary magnetic field. . While the implement
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